Seismology, Seismic Waves, Seismograph:
Seismology is the science, which deals with all the topics related to seismic waves. The seismic waves are the pulses of energy generated by earthquakes, which can travel through all parts of the earth. These waves can be measured and recorded by an instrument called Seismograph. A seismograph consists of a pendulum with a fixed pen, which marks zigzag lines on a paper called a Seismograph when an earthquake takes place. These lines show the intensity of the seismic waves These readings help to draw Homoseismal and Isoseismal lines on the map of the world. Out of these, the homoseismal lines show places that suffered the earthquake shocks at the same time. Similarly, the isoseismal lines depict the places which suffered the shocks equally.
Seismic reflections take place when a seismic wave traveling through a less dense material reaches a place where the density becomes much greater. On the other hand, the Seismic Refraction takes place when a seismic wave enters a less dense area from a place with much greater density.
What is a Seismograph?
A seismograph is a plain sheet or paper on which the seismic waves are recorded in the form of zigzag lines. These lines are drawn by instruments like Fossi-Forel Scale, Mercalli Scale, and Richter Scale. These scales are very sensitive to the vibrations and waves emitted by an earthquake.
Isoseismal and Homoseismal Lines:
Isoseismal lines are drawn on the world map, and these lines connect all those regions, which felt the earthquake at the same time. For example, an earthquake occurred at 11:13 am. These seismic waves traveling from the hypocenter reach different regions on the earth. In some regions, the seismic waves reach at 11:14 am, while in some regions they reach at 11:20 am. At a particular time, all those regions, which are under the shock of earthquake waves are known as Isoseismal regions. The line which connects the isoseismal regions is known as the ”Isoseismal Line”.
Homoseismal lines are drawn on the world map, which connects the regions that suffered the earthquake with the same intensity. Seismic waves lose their intensity as they start traveling away from the hypocenter. In different regions, the intensity of the earthquake varies. All those regions, which felt under the same intensity level of the earthquake are known as Homoseismal regions. The line, which is drawn to connect the regions of the same intensity are known as the Homoseismal line.
IsoseistaLines on maps that connect places of equal loud seismic vibrations.
Pliestoseistic Region/ Pliestoseista:
A Pleistoseista is a region bounded by Isoseista around the epicenter of the most widely received damage.
As the name implies the microseismic vibration of the earth’s crust is very smooth. Vibration is not felt except by a seismograph (earthquake vibration recording devices).
Macroseismic is the epicenter region that suffered the greatest damage